A typical photographic element contains multiple layers of light-sensitive photographic silver halide emulsions with one or more of these layers being spectrally sensitized to blue light, green light, and red light, respectively. The blue, green, and red light sensitive layers will typically contain yellow, magenta or cyan dye forming couplers, respectively.
For forming color photographic images, the color photographic material is exposed imagewise and processed in a color developer bath containing an aromatic primary amine color developing agent. Image dyes are formed by the coupling reaction of these couplers with the oxidized product of the color developing agent. Generally, image couplers are selected to provide image dyes with good stability towards heat and light and which desirably have an absorption curve with a suitable peak absorption and low unwanted side absorptions in order to provide color photographic images with good color reproduction.
The present invention is concerned with improving the light stability of yellow image dyes. Couplers that form yellow dyes upon reaction with oxidized color developing agent are described in such representative patents and publications as: U.S. Pat. Nos. 2,298,443, 2,407,210, 2,875,057, 3,048,194, 3,265,506, 3,447,928, 4,022,620, 4,443,536, and "Farbkuppler-eine LiteratureUbersicht," published in Agfa Mitteilungen, Band III, pp. 112-126 (1961). Other examples of yellow dye-forming couplers are detailed in Research Disclosure No. 365, Item 36544, September 1994, Section X-B(6). Such couplers are typically open chain ketomethylene compounds.
The ability of yellow image dyes to resist fade is important to the longevity of color images, especially those which are destined to be subject to prolonged storage or constant daylight exposure such as professional portraits and the like. Yellow images will fade and images formed with yellow dye as a component may change color if the rate of fade for the yellow dye is not sufficiently matched with the other dyes of the photographic element.
Heretofore, one method of improving the light stability of yellow image dyes has been to add one or more stabilizing addenda to the coupler dispersion. Compounds suitable for this purpose are described more fully in Research Disclosure No. 365, Item 36544, September 1994, Section X-D. However, stabilizing addenda can create adverse sensitometric affects. Furthermore, every addenda which must be added to an emulsion layer increases the cost of the product and creates additional manufacturing steps. U.S. Pat. No. 4,207,111 relates to couplers containing ortho chloro anilide and aryl ether substituents which are stated to provide light fastness.
There is still a need, however, for a yellow image dye-forming coupler which forms a dye upon development which exhibits improved light stability and desirable hue. It is particularly desirable to provide such a dye which requires little or no stabilizing addenda.